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Issued January 9, 1915. 

U. S. DEPARTMENT OF AGRICULTURE, 

BUREAU OF ANIMAL INDUSTRY. 

A. D. MELVIN, Chief of Bureau. 



THE ORIGIN OF THE' 1908 OUTBREAK OF FOOT-AND-MOUTH 
DISEASE IN THE UNITED STATES.^ 

By John R. Mohler, V. M. D., Chirf of the Pathological Division, Bureau of 
Animal Industry, aud Milton J. Rosenau, M. D., Director, Hygienic Labora- 
tory, United States Puilic Health and Marine-Hospital Service. 

Nature and Characteristics of the Disease. 

Foot-and-mouth disease, also known as aphthous fever, epizootic 
ajohtha, and eczema contagiosa, is an acute, highly communicable 
disease chiefly confined to cloven-footed animals and characterized 
by an eruption of vesicles on the mucous membrane of the mouth and 
on the skin between the toes and above the hoofs. The vesicles 
rupture, forming erosions and ulcerations; there is also salivation, 
tenderness of the affected parts, loss of appetite, lameness, emacia- 
tion, and diminution in the quantit}^ of milk secreted. 

The tremendous ravages of the disease are seen in the number and 
variety of the species attacked. While it may be regarded as essen- 
tially a disease of cattle, hogs would seem to be as easy a prey. 
Almost in the same grade of receptivity are sheep and goats. Next 
in order of susceptibility come the buffalo, American bison, camel, 
chamois, llama, giraffe, and antelope. Horses, dogs, cats; and even 
poultry, may occasionally become infected with the disease, the last 
three being particularly dangerous as carriers of the contagion. Man 
himself is not immune, and the frequency of his infection by com- 
ing in contact with diseased animals is established by numerous 
observations. 

The disease prevails in European countries and occasions great 
economic losses. The mortality is quite Ioav, the serious losses de- 
pending chiefly upon the diminution of the milk secretion and the 
loss of flesh in the affected animals. 

1 This article was originally issued June 16, 1909, as Circular 147 of the Bureau of 
Animal Industry, under the title " The Origin of the Recent Outbreak of Poot-and-Mouth 
Disease in the United States." 
71694''— 15 1 



2 OEIGIN OF 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 

Foot-and-mouth disease has made its appearance in the United 
States only on five different occasions— 1870, 1880, 1884, 1902-3, and 
1908. Its spread is very rapid among cattle, owing to the highly 
communicable character of the contagion, but fortunately every out- 
break upon American soil has thus far been quickly followed by 
its complete suppression. 

The causative agent of this disease has not been isolated, although 
numerous attempts have been made to cultivate and stain it. The 
experiments of Loeffler and Froesch in 1898 have shown that the 
virus will pass through the finest porcelain filters, thus indicating its 
ultramicroscopic size and the reason it has not been detected by 
staining methods. 

The specific principle may be found in the serum of the vesicles 
in the mouth and on the feet and udder; in the saliva, milk, and 
various secretions and excretions; also in the blood during the rise 
of the temperature. Animals may be infected directly, as by licking, 
and in calves by sucking, or indirectly by fomites such as infected 
manure, hay, utensils, drinking troughs, railway cars, animal markets, 
barnyards, and pastures. 

No definite immunity is rendered by an attack. The period of in- 
cubation is variable, usually from two to six days. The disease may 
appear in 24 hours after exposure. In exceptional instances the 
period of incubation is prolonged to 15 or even 18 days. 

FOOT-AND-MOUTH DISEASE IN MAN. 

Foot-and-mouth disease is primarily and principally a disease of 
cattle; secondarily and casually, a disease of man. The disease is 
transmissible to man through the ingestion of raw milk, buttermilk, 
butter, cheese, and whey from animals suffering from foot-and-mouth 
disease. It is also transmitted directly, though more rarely, from the 
salivary secretions or other infected material which may gain en- 
trance through the mucous membrane of the mouth. It is doubtful 
whether the disease can be transmitted to man by cutaneous or sub- 
cutaneous inoculation, though it is probable that the infection may be 
communicated if the virus directly enters the blood through wounds 
of any kind. Children are not infrequently infected by drinking 
unboiled milk during the periods in which the disease is prevalent 
in the neighborhood, while persons in charge of diseased animals ma}^ 
become infected through contact with the diseased parts or by milk- 
ing, slaughtering, or caring for the animals. 

The symptoms in man resemble those observed in animals. There 
is fever, sometimes vomiting, painful swallowing, heat and dryness 
of the mouth, followed by an eruption of vesicle? on the buccal mucous 
membrane and very rarely by similar ones on the fingers. The 

MAY. fH 5915 



JK OKIGIN OF 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 3 

vesicles appear on the lips, gums, cheek, and edge of the tongue, and 
are about the size of a pea. The vesicles soon rupture, leaving a small 
erosion which is soon covered by a thin crust under which the new 
formation of epithelium proceeds rapidly. The skin eruption mostly 
appears on the hands, tips of the fingers, base of the nails, volar sur- 
faces of the finger tips, and more seldom on the toes and other parts 
of the body. Besides these local changes, during the course of the 
disease there are occasionally observed headache, pain in the limbs, 
^ vertigo, abdominal cramps, vomiting, diarrhea, and weakness. The 
disease is very seldom fatal, usually appearing in a very mild form 
except in weakened children, in whom an accompanying intestinal 
catarrh may lead to a fatal termination. 

Veterinarians who have had considerable experience with the dis- 
ease among animals regard the human affection as by no means un- 
common in countries where foot-and-mouth disease prevails, but the 
disturbance of health is usually too slight to come to the notice of the 
family physician. 

Valentin was probably the first to suggest the infectiousness of 
milk and the transmissibility of the virus to man through the milk of 
diseased animals. He reported several cases where people became 
infected during the outbreak in Hesse in 1695. Sagar in 1765 re- 
ported a similar infection of men in Moravia from drinking infected 
milk. In 1778 all the residents of an Austrian monastery developed 
a vesicular eruption in- the mouth after drinking infected milk. 

Hertwig, Mann, and Villain conducted an experiment on them- 
selves in 1834 by drinking milk warm from a cow suffering with an 
attack of foot-and-mouth disease. Five days later vesicles appeared 
on the hands, fingers, tongue, cheeks, and lips of Hertwig, while the 
eruption in the other two was confined to the buccal mucous mem- 
brane. 

Allbutt observed the vesicular eruption in the mouths of three 
children in Yorkshire during the English outbreak in 1883, and ob- 
tained information of a number of similar cases in the community. 

During the 1883 outbreak in Germany a shepherd apparently in- 
fected himself by holding in his mouth a knife which had just been 
used in paring the diseased feet of his sheep. During this outbreak 
a number of milkmaids were infected through milldng, the vesicles 
appearing principally on their hands. 

In the Berlin outbreak of 1895 a number of those who drank in- 
fected milk developed fever, followed by the formation of vesicles 
on the tongue and lips. The acute disease lasted about five days, 
leaving a feeling of weakness for some time. Virchow made an in- 
vestigation of these cases and unhesitatingly pronounced the affection 
to be foot-and-mouth disease. 



4 ORIGIN OF 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 

A collection of the cases of this disease transmitted to man through 
the consumption of milk has been prepared by Wiu-zburg, while the 
work of Bussenius and Siegel contains a full bibliography of the 
literature of such transmissions up to 1896. 

Instances resulting from the use of butter made from infected milk 
are on record, while Schneider mentions instances where human in- 
fection followed the consumption of infected cheese. Friedberger 
and Frohner record cases which were caused by infected buttermilk. 

But few outbreaks of the disease have occurred in the United 
States, and therefore cases of its transmission to man in this country 
are quite rare. Law reports having observed the disease in man 
from drinking infected milk during the epizootic of 1870 in the East- 
ern States, but the outbreaks of 1880 and 1884 affected such a small 
number of animals and were so quickly suppressed that no instance 
of its transmission to man was recorded. A few cases have been re- 
ported by Brush ^ accompanying the New England outbreak of 1902. 
Similar reports have been likewise received concerning the appear- 
ance of vesicular eruptions in the mouths of children during the 1908 
outbreak, and the history of these cases incriminates the milk supply. 

Experiments by Loeffler and Froesch,^ as well as recent experi- 
ments which have been made in Denmark and Germany, indicate 
that the infection is comparatively easy to destroy by heat or the 
usual antiseptics. Milk pasteurized at a temperature of 60° C. for 
20 minutes is safe so far as infection by foot-and-mouth disease is 
concerned. 

HiSTOiiY OF Recent Outbreaks. 

On October 26, 1908, two carloads of cattle infected with or 
exposed to foot-and-mouth disease Avere sent from the stockyards 
at East Buffalo, N. Y., to Watsontown and Danville, Pa., respec- 
tively, from which points the disease was distributed to nine sepa- 
rate farms. It was upon these farms that the disease was brought 
to the attention of Dr. Leonard Pearson, State veterinarian of Penn- 
sylvania, who in turn notified the United States Department of 
Agriculture on November 10, and the diagnosis was confirmed on 
November 11 bj^ Dr. A. D. Melvin, Chief of the Bureau of Animal 
Industry, and Drs. Eice P. Steddom and John R. Mohler, chiefs, 
respectively, of the inspection and pathological divisions of the 
bureau. 

An endeavor was at once made to trace the disease from the 
affected cattle back to the point of origin, but at that time it was 
impossible to obtain any definite clue regarding the source of the 

1 Journal of the American Medical Association, vol. 40, June 20, 1902, p. 1700. 

2 Centralblatt fiir Bakteriologie, Parasltenkunde und Infectionskrankheiten, 1. abt., vol. 
23, 1898, p. 371. 



ORIGIN OF 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 5 

infection which would lead beyond the Buffalo stockyards. The 
only information which seemed at all significant was the fact that 
five bulls in the carload lot which went to Watsontown and two bulls 
in the car which went to Danville originated in the shipment of 
Mr. J. Jackson, living in the central portion of the State of Michi- 
gan. In order that this clue should be run down as quickly as possi- 
ble, an inspector was at once detailed to look up the origin of this 
shipment, while other inspectors at the same time were sent to points 
in Canada, Ohio. New York, and Indiana for the purpose of investi- 
gating the condition of the cattle remaining at the farms where 
• originated the balance of the cattle in the two carload lots which 
went to Watsontown and Danville from Buffalo. Eeports from 
all these inspectors were duly received and proved to be entirely 
negative. 

Subsequently (on November 22) a suggestive telegram was received 
from the Bureau of Animal Industry's inspector in charge at Detroit, 
Mich., and another telegram was received from a local veterinarian 
in the same city stating that a mild type of foot-and-mouth disease 
was prevailing on several farms in that vicinity. This diagnosis was 
confirmed on the following day, and it developed that among the 
animals infected with foot-and-mouth disease were 21 heifers which 
had previously been used b}^ Manufacturer A for the production of 
vaccine virus. This fact caused Secretar}^ of Agriculture James 
Wilson and Dr. Melvin, both of whom had gone to Detroit to make 
a personal investigation of the outbreak, to suspect the contamina- 
tion of the vaccine material used ; and inasmuch as the United States 
Public Health and Marine-Hospital Service, under the act of Con- 
gress of July 1, 1902, is charged with the supervision of biological 
products used in the prevention and treatment of diseases of man, the 
Secretary requested the cooperation of that service in an investiga- 
tion which was carried out by the writers of this paper. The char- 
acter of the lesions in the mouths and on the feet of the above-men- 
tioned animals indicated that the}'' were in the fourth stage of the 
disease, or the stage of healing, and that these lesions were older and 
more nearly healed than those found in any other center Avhere the 
infection had been observed. 

For these reasons, together with the fact that the outbreaks of 
foot-and-mouth disease in 1902 and 1903 were quite closely associated 
with the vaccinated cattle of the New England Vaccine Co.'s estab- 
lishment and Dr. E. E. Tyzzer's experimental work with vaccine 
at a farm at Wakefield, Mass., it was deemed advisable to make a 
thorough investigation of the movements of the 21 vaccinated cattle 
above referred to and to ascertain, if possible, what connection, if 
any, the use of these cattle for the production of vaccine virus by 



6 ORIGIN OP 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 

Manufacturer A had with the origin of the 1908 outbreak of foot- 
and-mouth disease. 

The outbreak of foot-and-mouth disease in Massachusetts during 
1902 started in Chelsea, and the place where it was thought to have 
originated was the farm of Mr. Owen Clark, who had a contract with 
Dr. C, of the New England Vaccine Co., to rent calves for the 
propagation of vaccine virus. These calves were later returned to 
Mr. Clark after the vaccine virus had been secured. Dr. C. occasion- 
ally obtained seed vaccine from outside sources to either strengthen 
or improve his product. He admitted having obtained a foreign 
strain, presumably of Japanese origin, through Manufacturer B, 
during the summer of 1902, while the outbreak in Mr. Clark's herd 
occurred in August of the same year. Although suspicion was 
directed to this source of origin of the 1902 outbreak, it was finally 
concluded that, as Mr. Clark's place was so near to Massachusetts 
Bay and the docks, there was some likelihood of the contagion hav- 
ing reached his farm through infected hay, straw, fodder, or other 
material from the trans- Atlantic steamers, and this explanation was 
quite generally accepted in lieu of more definite evidence. 

Later an independent outbreak of foot-and-mouth disease was 
started at AVakefield, Mass., in August, 1903, by Dr. E. E. Tyzzer, 
of Harvard Medical School, who w^as doing some experimental work 
in the study of vaccine bodies. He inoculated some calves on his 
father's farm with seed vaccine obtained from Dr. K. It was said 
that this virus also came from Japan, through Manufacturer B. 
As a result foot-and-mouth disease developed not only in the inocu- 
lated calves, but in the milch cows on the farm as well. The State 
of Massachusetts and the Bureau of Animal Industry subsequently 
had Dr. Tj^zzer repeat the experiments at an isolated stable in Wake- 
field that was rented for the purpose, and foot-and-mouth disease 
was again produced in this second series of inoculated cattle by the \ 
use of the same sample of vaccine virus. 

There is no question that Tyzzer succeeded in producing foot-and- 
mouth disease as a result of inoculation of vaccine virus which in 
some way had become contaminated with the virus of foot-and- 
mouth disease, and in his report to Dr. Salmon, then Chief of the 
Bureau of Animal Industry, he wrote : 

The mouth lesions and the vesicles occurring on the udders of the experi- 
ment animals presented a si3ecial type of necrosis and represent a process 
entirely distinct from vaccinia. * * * Two cows having passed through 
the eruptive disease described in this report were not immune to vaccinia, as 
has been shown by the inoculation of vaccine lymph and the subsequent micro- 
scopical study of the lesions. 

Drs. U. G. Houck and G. A. Johnson, who had been designated by 
the Bureau of Animal Industrv to make clinical notes on these cases, 



ORIGIN OF 1908 OUTBEEAK OF FOOT-AND-MOUTH DISEASE. 7 

state in their report that " the vaccine lymph used on both herds was 
responsible for the conditions that developed in them; that is, the 
production of a contagious disease, which, if it is not foot-and-mouth 
disease, the symptoms and lesions defy a differential diagnosis." 

However, there have always been an element of doubt and some 
contention with reference to the manner in which this vaccine became 
contaminated. The possibility that this vaccine virus, which had 
been removed from its original container, was contaminated by plac- 
ing it in an ice chest with specimens of foot-and-mouth disease at 
once suggested itself to Dr. Salmon. This, however, does not seem 
at all certain, particularly in the light of our present knowledge, 
although this view Avas apparently strengthened by the fact that four 
different series of experiments conducted at that time with vaccine 
obtained from the original source failed to produce any lesions recog- 
nized by the investigators as due to foot-and-mouth disease. The 
coincidence of having this outbreak occur in the quarantined section 
only two or three months after the last cases of the previous out- 
break had been eradicated threw further doubt upon the contamina- 
tion of the vaccine virus. 

With these facts in mind, and with the knowledge that the 21 
vaccinated cattle of Manufacturer A were among the first to show 
foot-and-mouth disease in the 1908 outbreak, the writers proceeded 
to the laboratories of this manufacturer, arriving November 30, 1908. 
The movements of these cattle w.ere at once investigated, with the 
result shown in figure 1. 

These cattle Avere purchased in September by Shaw Bros., who 
had a contract with Manufacturer A to furnish the animals for vac- 
cination purposes. After they had been vaccinated and the vaccine 
pulp removed, the cattle, as was the custom, were returned to Shaw 
Bros., who received a rental price for each animal and subsequently 
disposed of them to the public. In this particular instance the ani- 
mals were vaccinated on September 23 and October 6, and turned 
back to Shaw Bros. October 16, on which date they were driven 
to the Haley Commission Co.'s pens in the Detroit stock 3^ards, 
watered and fed for two hours, and then taken to a town 15 miles 
distant, where they were dispersed. The appearance of foot-and- 
mouth disease was observed on October 18 by Mr. I, W. Shaw, who 
purchased 10 of these animals, and by other purchasers about the 
same time. 

In obtaining a record of all shipments that subsequently passed 
through the pens of the Haley Commission Co., which presumably 
became infected by the 21 vaccinated cattle, it was quite interesting 
to learn that the healthy cattle, previously referred to as having been 
collected by Mr. J. Jackson, were shipped to the Haley Commission 



^ 



ORIGIN OF 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 




P O c3 

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ORIGIN OF 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 9 

Co. on October 20 and all but 32 sold. The latter animals were 
reshipped to East Buffalo on October 23 and evidently carried the 
contagion from the infected pens of the Haley Commission Co. to 
the Buffalo yards, and thence by means of the 7 bulls in the consign- 
ment to Watsontown and Danville, Pa., as already mentioned. All 
subsequent centers of infection were directly or indirectly traced to 
the 21 vaccinated animals as the' original source of infection. All 
other shipments which passed through the Haley Commission Co.'s 
pens for six days previous to the receipt of the vaccinated cattle were 
traced to their destinations with negative results, while negative 
results also followed the investigation of places whence these 21 
cattle came before they were taken to the vaccine stables of Manu- 

f acturer A.. 

The likelihood of the infection of these cattle through vaccination 
at the latter's plant having been indicated, three separate strains of 
vaccine virus which had been used by the firm during 1908 were 
secured. The experiments performed with these three lots of vaccme 
virus are here briefly recorded. 

Experiments with Vaccine Virus, 

first series of experiments. 

These experiments with seed vaccines obtained from Manufacturer 
A were made jointly by the writers of this paper, assisted by^ Dr. 
E C. Schroeder and Mr. W. E. Cotton, of the Bureau of Animal 
Industry, at the bureau's experiment station, Bethesda, Md. A 
cement stable was erected for the purpose of making these tests, and 
special care was at all times maintained to prevent any experimental 
error. One attendant, who had never seen foot-and-mouth disease, 
and had not recently been employed among cattle or other live stock, 
was transferred to the work of caring for these experiment animals. 
All animals were kept under observation continuously for at least two , 
weeks before the experiments were made, and in all cases the mouths 
and feet were carefully examined before injections were made. The 
three strains of vaccine virus tested in this series of experiments 
were obtained from Manufacturer A by the writers during a joint 
visit and were kept in possession of one of them (Rosenau) until, 
the package was broken and the vials opened immediately before 
use. The entire work was carried out in a careful manner and every 
effort made to prevent outside contamination. 

The clinical notes are as follows : 

Calf 625.— This heifer calf, about S^months old, was inoculated December 
14, 190S, by scarifying the skin of the abdomen in three different areas, one 
area being inoculated with each of the strains of virus obtained from Manufac- 
turer A and known, respectively, as the J strain, the D strain, and the Manu- 
71004°— 15 2 



10 ORIGIN OF 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 

facturer B strain. This calf, which had not been previously used for producing 
vaccine virus, developed typical vesicles and pustules of cowpox, but did not 
show any indications of foot-and-mouth disease. 

Three other heifer calves, Nos. 675, 676, and 674, about 5 weeks old, were 
inoculated intravenously December 14, 1908, with the J strain, the D strain, 
and the Manufacturer B strain, respectively. These animals were obtained 
from a local vaccine manufacturer, and having been used for the propagation of 
vaccine virus were immune to cowpox. Qilves 675 and 676, inoculated with the 
J and D virus, remained healthy and failed to show any indication of dise;!se 
following their injection. On the other hand, calf 674, which had been inocu- 
lated similarly with the Manufacturer B strain, developed lesions of foot-and- 
mouth disease as recorded in the following : 

Calf 67/f. — December 14: Injected intravenously in right jugular vein with 
2 c. c. of Manufacturer B's vaccine. 

December 26: No indication of foot-and-mouth disease. 

December 28 : A small papule with a gray center about 2 mm. in diameter is 
noted on the gum of the upper jaw just above dental pad. This is the third 
papule of this character to make its appearance, the first being on the outside 
of the lower lip just at its margin, and tlie second inside the lower lip. All 
four feet from ankle down somewhat swollen and reddened. 

December 29 : Papule noted above has broken and left only a small eroded 
area. A fresh one is forming on gum of lower jaw. Swelling of feet has sub- 
sided, except in the left hind one, which is also much reduced. 

3.30 p. m. : The papule noted above now has a small gray center. 

December 30 : The papule found yesterday appears to-day as a small erosion. 
Interdigital space of left hind foot reddened, other feet normal. 

January 2, 1909: Two small vesicles have develoi>ed and broken on right side 
cff tongue; one new one forming on right side of inner lower lip. Vesicles have 
formed and broken in interdigital space of both hind feet. 

January 4: One small erosion, covered by an ulcerating surface on outside of 
lower lip near its margin. Lesions on side of tongue noted January 2 have 
disappeared: Lesions in interdigital spaces are commencing to heal. 

January 7 : One new hyperemic patch about 3 mm. in diameter is forming on 
inside of lower lip. 

January 8: Lesion noted yesterday is now fairly well developed and has a 
gray necrotic center. One reddened papule in interdental space on right side of 
lower jaw. 

January 18 : A number of small superficial erosions, more or less circular in 
outline, on under side of tongue. At the peripheries of each there is a narrow 
zone of very thin brown epithelium, which is loosened fi'om the basement 
membrane. 

January 19 : Erosions present on under side of tongue yesterday have par- 
tially coalesced. There are three similar circular areas on dorsum of tongue, 
from which the superficial layer of the mucous membrance has been eroded, 
leaving the papillfe still intact. 

The temperature, taken twice daily since date of inoculation, has never ex- 
ceeded 39.7° C. 

January 20: The desquamated areas on the tongue have coalesced and in- 
creased in size. Killed. Head and left hind foot preserved as specimens. 

The interesting feature in this case was the subsidence of the primary lesions 
and the subsequent recurrence of active erosions. 

Coif 656. — December 29, 1908: Injected intravenously in right jugular vein 
with saliva and material from papule which had formed on gum of calf 674, 
mixed with sterile salt solution. 



ORIGIN OF 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 11 

December 30, 9 a. m. : Nothing abnormal. 3.30 p. m. : A number of red 
papules have formed on the hard palate. 

December 31: A few more slightly raised reddened areas with gray centers 
have developed on upper lip. 

January 2, 1909 : The lesions have not progressed to any further stage of 
development and are gradually fading away. 

January 4: No lesions. The highest temperature recorded was 39.4° C. 

January 9 : Killed and buried inunediately without autopsy. 

Calf 65'/. — An area scarified on inside of lower lip and one on gum corre- 
sponding to it were inoculated December 29, 190S, with material scraped from 
papule which had formed on gum of calf 674. On the fourth day a considerable 
number of reddened papules formed on inside of lower and upper lips and on 
hard palate. Similar hyperemic zones were noted on the gums of the lower jaw 
on the sixth day. These showed a dry grayish center on the following day, 
which on being removed left a small erodeil surface without any fluid being 
visible. Other lesions of a similar character appeared at irregular intervals on 
the mucous membrane of the gums, lips, and hard palate until January 11, after 
which all the remaining lesions gradually disappeared. The highest temperature 
observed was 39.6° C. On January 20 the calf was killed and the head pre- 
, served. 

Calf 623. — Inner side of lower lip scarified and inoculated January 2, 1909, 
with scrapings from lesions on lip of calf 654. On the fourth day several small 
circular areas, each covered by a gray scab, had formed at seat of scarification. 
These scabs disappeared on the following day, leaving small eroded areas. On 
the sixth day a large eroded area appeared on the dental pad and hard palate 
which .soon became eroded and covered by a thin brownish exudate. This area 
increased in size on the following day coincidentallj^ with the appearance of 
reddened papules on the gums, interdental space, and inside of lower lip. 
Similar lesions continued to appear at irregular intervals until January 23, 
when one or more large reddened patches were noted on nearly every trans- 
verse ridge of the hard palate. On January 25 the epithelium over these areas 
began to erode, the color gradually fading. Several small desquamated areas 
and two shallow erosions appeared on the gums behind the incisors and in the 
interdigital space, respectively. The highest temperature observed was 39.3° C 
Animal killed February 27. 

Cow 333. — The right side of inner surface of lower lip scarified and inocu- 
lated January 9 with material scraped from lesion in mouth of calf 623. On the 
second day a few small ero.sions partially covered with scabs appeared within 
area of scarification. By the fourth day several new red circular lesions of the 
usual character had formed within and contiguous to area of scarification. On 
the following day about 15 small circular erosions with graj^ necrotic centers 
were noted within and contiguous to the area of scarification. Five days later 
several small reddened patches appeared on the inside of the lower lip and the 
gums below the inci.sors. 

January 20, injected into left jugular a small quantity of material from 
mouths of calves 674 and 654, which was mixed with 4 c. c. sterile salt solution. 
Several small reddened areas on hard palate appeared January 23. Two days 
later one shallow circular erosion about 8 mm. in diameter developed on gum 
of lower jaw. On the following day three small reddened patches with eroded 
centers were noted on hard palate; the small erosion still present on gum of 
upper jaw. About the same condition was observed three days later except 
that the lesions last noted were gi'adually disappearing. Highest temperature 
recorded was 39.1° C. Animal killed and buried February 11. 



12 OEIGIN OF 1908 OUTBEEAK OF FOOT-AND-MOUTH DISEASE. 

Calf 677. — February 5: Inside of lower lip scarified and inoculated with 
scrapings from the lesions of calf G23 and cow 333. 

Februai-y 9 : A considerable number of small, very superficial erosions within 
the scarified area ; one a short distance outside and another on opposite side 
of lower lip. 

February 10: On the upper surface of tongue there are three circular areas 
about 3 cm. in diameter where the epithelium has become desquamated. On 
under side of tongue there are also two small eroded areas. 

February 11 : A considerable number of small red papules with small gray 
centers within and surrounding the seat of scarification, some of them being a 
considerable distance removed. On dorsum of tongue there are a number of 
circular and elliptical areas where the epithelium has become eroded, leaving 
the papillae and basement membrane intact. On inferior and lateral surfaces 
there are a number of similar raw surfaces, in some of which a narrow rim of 
desquamated epithelium remains attached to the periphery. The saliva is 
unu.sually thick and viscid. One small irregular erosion about the size of a 
bean is noted in the cleft of the left hind foot. 

February 12: Many of the lesions on dorsum of tongue have coalesced; fully 
two-thirds of the epithelium has been desquamated. The lesions on sides and 
under surface of tongue have increased in size. There are a considerable num- 
ber of red papules on gums of upper jaw, in the interdental space of lower jaw, 
and on the hard palate. The lesion in the interdigital space of the left hind 
foot shows no change. 

February 13: Nearly all the epithelium has been stripped from the tongue. 
Many papules still present on inside of lip and on gums and a few new ones 
on hard palate. One small eroded lesion in interdigital space of each hind foot. 

February 15 : The epithelium of the tongue which has been exfoliated is 
now replaced by new tissue, leaving the tongue again normal with the excep- 
tion of a small erosion on the inferior surface. There are several papules on 
hard palate and on inner side of lower lip. The lesions in interdigital spaces 
of hind feet have about disappeai-ed. 

February 16: Many red patches with eroded centers on hard palate. A few 
on both upper and lower lips. The highest temperature that has been recorded 
was 39.6° C. 

March 6 : No lesions apparent. On this date cow 375, occupying a corner 
stall in the same stable with this calf (677), was inoculated intravenously 
with material from the mouth of calf 609, which had been injected with vaccine 
from Manufacturer B. 

March 11 : Calf 677 has an erosion about 15 by 30 mm. on dorsum and right 
side of tongue and a similar one about 5 mm. in diameter a short distance in 
front of the other. Morning temperature, 40.3° C. ; afternoon, 40° C. 

March 12: The smaller area noted yesterday has increased to about 15 mm. 
in diameter. The longer one is about the same size as it was yesterday. Both 
are coated with a brownish-yellow exudate. Three additional erosions have 
appeared on dorsum and left side of tongue, each from 10 to 15 mm. in diameter. 
Three erosions, each about 12 mm. in diameter, have made their appearance 
on anterior portion of dental pad and upper lip near median line, and have 
coalesced, fragments of the desquamated epithelium being still present. Near 
by, on the upper lip, a vesicle about 1 cm. in diameter broke while the animal 
was being examined. The vesicle was very flat and appeared to be simply a 
circular white area in which the epithelium had become separated from the 
basement membrane. The amount of serum present, if any, was so small as to 
escape observation. On the inside of the lower lip there is a very shallow 
erosion about 3 uuu. in diameter. No lesions on feet. 



OEIGII^ OF 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 13 

March 13 : Tlie lesions on the tongue have commenced to heal. A new eroded 
area has made its appearance on the buccal membrane,' just back of the first 
molar tooth, left side. Killed at 4 p. m. A small whitish area, apparently a 
vesicle just forming, was found after death in the interdigital space of one of 
the fore feet. The head and foot were preserved in Kaiserling's fluid. 

This case is particularly interesting on account of the recurrence of the lesions 
as a result either of autoinfection or of exposure to cow 375, which suffered 
from a more severe form of the disease. 

Cow 375. — Februai-y 11 : Moved into infected stable where the previously men- 
tioned cases were kept to receive natural exposure to foot-and-mouth disease. 

Februaiy 11 to March 5 : No lesions. 

March 6, 4 p. m. : Injected intravenously with 5 c. c. of an emulsion of desqua- 
mated mucous membrane from calf 609 (see third series of experiments), which 
contracted foot-and-mouth disease as a result of the inoculation of Manufac- 
turer B's vaccine. 

March 10: Yesterday afternoon animal refused to eat; the flow of saliva was 
increased. This morning she has an erosion fully 2 cm. in diameter on side 
of lower lip ; there is a second one about li cm. in diameter on buccal mem- 
brane, immediately back of the right commissure of lips. There are also 
several small erosions in this region and a few on opposite side of mouth. The 
tongue is very sensitive and a vesicle is forming at its tip. Considerable 
drooling from the mouth ; also clear discharge from nostrils. No lesions on 
feet. Animal eats very little. The temperature yesterday morning was 38.4" 
C. ; afternoon, 39.6° C, while this morning it was 38.7° C, and remained about 
this height until the animal was killed (March 13). Yesterday afternoon's 
temperature was the highest observed during the experiment. 

March 11 : Large amount of ropy saliva drooling from the mouth. The two 
large erosions noted yesterday, which were then very red, raw-looking surfaces, 
are now coated with a thin grayish lymph. The several small erosious noted 
then have increased in size and are coated with the same kind of an exudate. 
Several large, white, circular vesicles have made their appearance on the dental 
pad. The epithelium of the entire tip of the tongue has disappeared, leaving 
a large raw surface. The right front foot has large vesicles filled with serum 
at both the front and rear of interdigital space and on bulbs of heel. The 
right hind foot is in a similar condition, with the exception that the vesicles 
have broken and serum can be pressed out of them. The left hind foot is in 
much the same condition as the right hind one. The left fore foot is also 
similarly afiiected, but not to the same degree as the others. 

March 12: Lesions in the mouth much the same as yesterday, excepting that 
the white circular vesicles on the pad are now raw surfaces, the loosened 
epithelium having disappeared. Two additional large erosions which have 
coalesced found on dorsum of tongue. The vesicles on feet have nearly all 
broken, leaving raw and eroded surfaces partly covered by the desquamated 
epidermis. The animal is very lame. There is still considerable drooling from 
mouth. 

March 13 : The earlier lesions in mouth and on tip of tongue are beginning 
to heal. The feet are very sore, large raw surfaces being present within and 
behind and in front of the interdigital spaces. In some places the desquamated 
epidermis is still attached. Killed at 4 p. m. The head and all four feet pre- 
served. 

Cow 630. — March 10, 4 p. m. : Moved to infected stable and placeil l)etween 
cow 375 and calf 677 as a cohabitation experiment. 

March 15: An elevated vesicle about 15 mm. in diameter has formed on left 
side of tongue. It has broken (10 a. m.), leaving a small opening in the center, 



■14 ORIGIN OF 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 

and the desquamated epithelium is still attached at the periphery of lesion. 
No other lesions. The highest temperature recorded was 38.8° C, which 
occurred this afternoon, while the morning temperature was 38.3° C. 

March 16: The epithelium is completely eroded from the area noted on 
tongue yesterday. The right side of upper lip is thickened, and what appears 
to be a spherical vesicle 2 em. in diameter is forming and nearly ready to break 
on the mucous surface. On the inner surface of opposite side of the lip there 
is a flat vesicle about 12 mm. in diameter. On the end of tongue a slightly 
raised vesicle fully 2 cm. in diameter is noted. If a little pressure is exerted 
in this region blood oozes from the fungiform papillne within the affected area. 
There is some drooling. Animal eats fairly well. A small area within inter- 
(Ugitnl space of left front foot seems sensitive, but no lesions yet visible. Killed 
at 3.30 p. m. Head and left foot, the latter showing two small vesicles in 
interdigital space, preserved. 

Calf 61Ji. — March 13 : Moved to infected stable for a natural exposure ex- 
periment after cow 375 and calf 677 had been killed. It was placed as far away 
• from where these animals had stood as the inclosure would permit. 

March 15 : One erosion about 1 cm. in diameter and two raised white vesicles, 
each about 5 mm. in diameter, on dorsum of tongue. Two small, very fresh 
■erosions on gums of lower jaw below the incisors. 

March 16: The white vesicular elevations noted yesterday as being on the 
dorsum of the tongue are now erosions 15 mm. or more in diameter; the one 
'to the right of the median line has become confluent with an erosion noted yes- 
terday, leaving a raw surface lA by 3 cm. in diameter. Still another erosion, 
1 cm. in diameter, has appeared on the dorsum of the tongue. There are now 
three erosions, each about 15 mm. in diameter, on gums of lower jaw below the 
incisors, and another 10 by 15 mm. inside of the lower lip, 2 cm. from median 
line. A very sensitive spot is noted within the interdigital space of the left 
fore foot. At 3.30 p. m. : A large amount of clear viscid fluid is being dis- 
charged from nose and mouth. It is so viscid that it hangs down in long strings 
from each side of the month. Killed. Head and left fore foot preserved. A 
vesicle was beginning to form on the inner side of one of the bulbs of the heel 
:of left fore foot. The highest temperature recorded for this animal was 
•.3r>.5° C, which occurred this morning. 

It should be noted that in the hist two instances, cow 630 and calf 
Gl4, foot-and-mouth disease obtained from vaccine virus was trans- 
mitted by natural modes of infection. 

During the course of this series of experiments ample opportimity 
had been offered for the disease to spread to susceptible animals which 
cohabited with the inoculated cattle. This, however, did not occur 
until the introduction of the virus from calf 609 (third series of 
experiments) into cow 375 on March 6, where it assumed such an 
exalted virulence that cow 630 and calf 614 readily contracted the 
disease by natural exposure. For instance, calf 675 was kept in the 
foot-and-mouth-disease stable from December 14 until it was slaugh- 
tered on January 20; calves 676 and 625 w^ere likewise kept in this 
.stable from December 14 until January 9 ; cow 173 from January 20 
to February 27; cow 375 from February 11 to March 5; hog 2449 
from February 11 to February 27; sheep 34 from February 11 to 
February 27, and two male iambs from February 20 to March 11, 



OEIGIN OF 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 15 

but without presenting any lesions of foot-and-mouth disease. The 
only explanation that appears tenable for this absence of natural 
transmission of the disease is that the virus had become greatly 
attenuated, probably as a result of its admixture with vaccine virus, 
and it required passage through a particularly susceptible individual 
before it became exalted in virulence. 

This same lack of virulence was observed in the disease as it 
occurred at the beginning of the 1908 outbreak. Five of the 21 
vaccinated calves of Manufacturer A were taken to two farms, 
and although they were permitted to commingle with the cattle on 
these farms continuously, no occurrence of the disease at these places 
took j)lace. On the other hand, foot-and-mouth disease developed on 
every farm where the remaining 16 cattle were taken. 

In order that vaccinia (cowpox) could definitely be eliminated in 
making a diagnosis of the disease being produced by vaccine virus, 
it was thought desirable in addition to using vaccinated calves (im- 
mune to cowpox) to check the work further by inoculating guinea 
pigs on the scrotum and rabbits on the cornea with scrapings from 
the lesions produced in the calves. This was done by one of us 
(Mohler) in the first five cases, and the work was duplicated by the 
other (Eosonau) in three of the cases with entirely negative results. 

It will be recalled that of the tliree strains of vaccine obtained 
from Manufacturer A, the only strain which proved to be contami- 
nated with foot-and-mouth disease virus was obtained from Manu- 
facturer B, and the records showed that this virus was received by 
Manufacturer A in May, 1908, In order to ascertain if this latter 
vaccine was contaminated at the time of its propagation, the estab- 
lishment of Manufacturer B was visited and seed vaccine from five 
different lots was obtained for inoculation into sheep and calves, 
which experiments will be described below. 

SECOND SERIES OF EXPERIMENTS. 

The establishment of Manufacturer B was visited by the writers on 
February 1 and 2, and the records of the various vaccine seeds were 
examined, especially as to their origin and the character of lesions 
produced in the vaccinated calves. Five different lots of vaccine were' 
obtained and experiments were at once started with a particular 
virus, for convenience termed " vaccine V." This strain was the same 
as that which had been procured by Manufacturer A. About 10 c. c. 
of this vaccine virus was obtained in a glass pipette, both ends of 
which were sealed in a flame, and the material was kept in the pos- 
session of one of us (Mohler) until used. 

Sheep were used for this experiment, and they were kept in one 
of the animal rooms in the new laboratory building of the Depart- 
ment of Agriculture, where no experiments in foot-and-mouth dis- 



16 ORIGIN OF 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 

ease had been conducted. These animals, with one exception, had 
been raised at the bureau experiment station, and all had been under 
close observation for at least three weeks before the inoculations were 
made. This series of experiments was conducted personally by Dr. 
Mohler assisted by Dr. Eichhorn and an attendant who had not seen 
foot-and-mouth disease and had not been anywhere near the infected 
districts. Before the pipette containing the vaccine was opened it 
was submerged first in a 5 per cent solution of carbolic acid, and 
then in 95 per cent alcohol. A small quantity of the contents was 
then emptied into a sterile crucible and 1 c. c. drawn up into a 
syringe which had just been sterilized. Every possible precaution 
was observed in order to prevent any outside contamination and to 
be able to connect definitely with the vaccine under investigation any 
positive results which might be obtained. 

Sheep 1. — This animal was born at the experiment station and was about two 
years old. It had been vaccinated with uncontaminated vaccine virus during 
January and was therefore immune to vaccinia. 

February 5: Injected intravenously in right jugular with 1 c. c. of Manufac- 
turer B's vaccine V. 

February 6 : Temperature 39.0° C. Appetite good. No lesions. 

February 7 : Temperature 40.5° C Appetite fickle. No lesions. 

February 8 : Temperature 40.6° C. Refuses its feed. Has been lying down 
since 8 a. m., when the attendant arrived. At 9 a. m. the sheep is made to rise 
but holds left fore foot off the ground, flexing it rapidly, apparently from pain. 
On walking lameness is shown in this foot and there is considerable heat noted 
above the coronet. On examining the interdigital space of this foot two elon- 
gr.ted vesicles are observed, one on each claw, raising the epiderm of the soft 
skin, just above its attachment to the horn. On pulling the toes farther apart 
both vesicles ruptured, liberating a clear, watery serum. No mouth lesions. 

February 9: Temperature 41.9° C. Both fore feet show erosions which ex- 
tend from the anterior to the posterior border of the interdigital space, involving 
principally the soft skin adjacent to the coronary band. Animal is quite lame 
In these feet and also in the left hind foot. The latter is also found to contain 
an eroded elongated patch at the juncture of the skin with the horn of the hoof, 
and a small pea-sized vesicle is just forming in the posterior part of the cleft. 
No lesions in the mouth. Killed at 4 p. m. and three legs preserved. Blood 
defibriuated and injected into sheep 2. 

Sheep 2. — February 9 : This animal, a western sheep which had been under 
observation for 6 weeks, was injected intravenously in right jugular with 
1 c. e. of filtrate of blood from sheep 1. 

February 10: Temperature 39.1° C. No lesions. 

February 11 : Temperature 39.5° C. No lesions. 

Februiiry 12: Temperature 40.1° C. The first indication of disease outside 
of the temperature and fickle appetite is noted to-day in that the animal is quite 
lame in the right front foot. On examination a small vesicle about the size of a 
kidney bean is observed in the front part of the cleft between the digits, while 
there is a hyperemic zone around the outside border of the coronet. The mouth 
and other feet appear normal. 

February 13: Temperature 39.3° C. The vesicle which was observed in the 
cleft of the right front foot yesterday has ruptured and an irregular erosion 
with reddened base and partly covered around the borders by necrotic epiderm 



OKIGIN OF 1908 OUTBREAK OP FOOT-AND-MOUTH DISEASE. 17 

has taken its place. Several minute vesicles are noted above the coronary band 
on the outside claw, while above the heel of this claw is a moist erosion, evi- 
dently the result of a recently ruptured vesicle. No other lesions apparent, 
although the mouth and other feet were carefully examined. Killed at 3 p. m. 
Material was obtained from the vesicles and erosions for inoculation of sheep 3. 

(It should be noted here that some of the filtrate obtained from sheep 1 was 
also injected intravenously into a cow and a Bardados sheep, but without pro- 
ducing any lesions. The injections of these latter cases, however, were not made 
until February 11, forty-eight hours after the filtrate had been obtained, during 
which interval it was kept in a refrigerator.) 

Sheep S. — This animal was a yearling born at the experiment station and 
kept under close observation since January 1. Like sheep 1, it had been made 
immune to vaccinia by cutaneous scarification and inoculation of normal vac- 
cine virus. 

February 13: Injected intravenously in right jugular vein with 1 c. c. of 
fluid prepared by adding physiological salt solution to the material obtained 
from lesions in sheep 2. 

February 14 : Temperature 39.1° C. Apparently normal. 

February 15: Temperature 41" C. Animal lying down most of the day. 
Appetite capricious. Quite sensitive if pressure is applied to cleft of left front 
and right hind foot. 

February 16 : Temperature 40.9° C. Sheep Is very lame in front and par- 
ticularly so in right hind leg, which is scarcely placed on the ground in walking. 
On examination this foot is seen to have a vesicle the size of a marrow-fat 
bean in the fold of skin in front of and between the digits above the inter- 
digital space. Two erosions which are still moist and partly covered by de- 
nuded epiderm appear in the posterior part of the cleft and involving both 
heels. Blood is slowing oozing from the eroded surface. The left fore foot has 
an erosion on each claw running along the soft skin immediately above the horn 
of the hoof, very similar to the lesion described in the same foot of sheep 1. 
The right front foot shows a hyperemic area which is quite sensitive directly 
in the middle of the iuterdigital space. A small flat vesicle about the size of a 
split pea is forming on the glome of the inside digit. Directly in front of this 
on the outside coronet is a small eroded patch irregular in outline, which is 
covered with a grayish exudate of lymph. A marked erythema is noted above 
the coronary band of both digits of this foot. No mouth lesion. Animal killed 
at 4 p. m. Two legs preserved. 

During this series of experiments sheep 4 and lamb 5 were con- 
tinuously exposed to the infected sheep 1, 2, and 3, eating of the 
same hay, and frequentl}'^ from the same feed box, but in neither case 
was the disease transmitted by such cohabitation. It should also 
be stated in passing that material from the vesicles and erosion in 
each of the infected sheep was rubbed well into scarified areas on 
the scrotum of a guinea pig and applied to the slightly abraded 
cornea of a rabbit, but in no case were lesions of vaccinia produced. 

THIRD SERIES OF EXPERIMENTS. 

This series of tests was made independently by one of us (Eosenau) 
in the Hygienic Laboratory, United States Public Health and 
Marine-Hospital Service. 



18 ORIGIN OF 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 

The rooms in which the experiments were carried on were just 
finished in a new wing of the building, and had never been used for 
any other purpose. The inoculations were made personally by Dr. 
Rosenau, assisted by Dr. Frost. The care, of the animals was in- 
trusted to two janitors. None of the persons mentioned had been 
near any case of foot-and-mouth disease, nor had any of them had 
any association with cattle or sheep. 

The animals used in this series were four young calves which had 
previously been used by a local manufacturer for the propagation of 
vaccine virus. They were obtained from a district entirely free from 
foot-and-mouth infection. They were under continuous observation 
for 20 days before the experiments were attempted. 

The two strains of vaccine virus used in this series of experiments 
were personally obtained by one of us (Rosenau), who made inde- 
pendent trips to the establishments of Manufacturers A and B partly 
for this purpose, in order that there might be no connection or con- 
tamination with the virus used in the other experiments. Each strain 
of virus was obtained in a carefully sealed package and not opened 
until the moment of use. Before opening the vials they were im- 
mersed in bichlorid of mercury solution (1 to 500) in order to elimi- 
nate any outside contamination. In short, every possible precaution 
was taken to guard against all sources of experimental error. 

Four calves immune to vaccinia were given an intravenous in- 
jection of the virus. The protocols are as follows: 

Calf 609. — Black female, about 4 weeks old. Vaccinated February 13. All 
Incisions sbowed typical vesicles. Vaccine material taken February 19. 

March 1 injected intravenously with 2 c. c. of glyceriuated vaccine virus V 
of Manufacturer B. 

On the fourth day vesicles appeared on dorsum of tongue, followed by desqua- 
mation of epithelium, leaving a large, sharply defined, and typical punched-out 
ulcer with deep reddened base, papillae intact, and containing a small island of 
Intact mucous membrane. In addition there were a few other smaller vesicles 
containing clear fluid. Salivation; no foot lesions; temperature rose to 39° C. ; 
marked weakness. Animal killed on fifth day. Tongue preserved. 

Calf 611. — Red male, about 5 or 6 weeks old. Vaccinated February 13, 
Tj^pical take along all incisions. Vaccine material taken February 19. 

March 1 given intravenous injection of 2 c. c. glyceriuated vaccine virus V 
of Manufacturer B. 

Forty-eight hours later three dark red congested macules appeared on ventral 
surface of tongue, two of which disappeared about twenty-four hours later ; 
the third formed a vesicle, which ruptured within two days, leaving a super- 
ficial erosion which rapidly healed. During this time there were excessive 
secretion of viscid saliva and slight reddening of the margin of gums. Tem- 
perature rose to 39.6° C. on second day. 

On the eighth day a small vesicle appeared on inside of upper lip, and inside 
of left cheek a papilla denuded of mucous membrane was noted, also three small 
red spots on the hard palate which continued till the animal was killed. 

On the tenth day another erosion appeared on upper lip and tip of tongue. 



OKIGIN OF 1908 OUTBEEAK OF FOOT-AND-MOUTH DISEASE. 19 

Coincideut with first appearance of these month lesions a small erosion 
appeared in the interdigital space of left hind foot, evidently a ruptured vesicle. 
By the eighth day the skin of the whole interdigital space of this foot was 
white, soft, necrotic, and perforated in several places with irregular small 
ulcers with reddened bases. In a corresponding position on the right hind 
foot appeared on the fourth day also several reddened spots and erosions. 

On the ninth day a large vesicle appeared, occupying practically the whole 
of the interdigital space of the left fore foot, which ruptured and exuded a 
clear sanious fluid. 

Killed on the tenth day. Specimens preserved. 

Calf 610. — Ked-and-white female, about four weeks old. Vaccinated Feb- 
ruary 13. All incisions showed typical vesicles. Vaccine material scraped 
February 19. 

March 1, inoculated intravenously with 4 c. c. glycerinated vaccine virus 
which Manufacturer A obtained from Manufacturer B. 

On the second day two small papules developed on margin of tongue, which 
disnppoared on the fourth day. Margin of gums reddened and a small superficial 
erosion developed on gums near central incisor teeth. On hard palate poste- 
riorly appeared three large reddened maculse. Centers of each spot became 
grayish and necrotic. Other similar patches subsequently developed on the 
pharynx. 

An eczematous condition developed around anterior margin of interdigital 
clefts of both hind feet on second day, with subsequent formation of minute 
ve.sicles which quickly dried. In interdigital space of left hind foot a small 
vesicle appeared on the sixth day, which broke, forming an erosion which 
rapidly healed. 

Killed on the tenth day. 

Calf 612. — Red-and-white female, about five or six weeks old. Vaccinated 
February 13. Gave good take, all incisions showing typical vesicles, which 
were removed February 19. 

March 1, injected intravenously with 4 c. c. glycerinated vaccine virus which 
Manufr.cturer A procured from Manufacturer B. 

About the seventh day, redness of margins of gums, salivation. Small ulcer on 
dental pad. Small superficial ulcers on gum anteriorly and one in angle of 
mouth. Mucous membrane of pharynx red and congested. Mild eczematous 
condition of skin about interdigital cleft ; no vesicles. Killed on the tenth day. 

Diagnosis. — Calves 609 and 611 had typical clinical pictures of foot-and- 
mouth disease. The diagnosis was confirmed by Drs. Melvin, Mohler, Ben- 
nett, Eichhorn, Formad, Ditewig, and several others, who saw the animals after 
the lesions were well advanced. 

It is believed that Calves 610 and 612 also had foot-and-mouth disease of a 
benign type. 

RESULTS SHOW CONTAMINATION OF VACCINE VIRUS. 

It must appear evident from the clinical notes presented in the 
above three series of experiments that the vaccine virus propagated 
by Manufacturer B in April and May, 1908, was contaminated with 
the virus of foot-and-mouth disease. The history of this particular 
vaccine shows that it was a Japanese strain, imported for the pur- 
pose of improving the standard of vaccine produced by that com- 
pany. The fact that the foot-and-mouth infection was present in the 
vaccine virus of Manufacturer B for so long a period, but was not 



20 ORIGIN OF 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 

transmitted to outside cattle, was doubtless due in part to this jfirm's 
practice of killing its calves after taking the vaccine virus. Manu- 
facturer A, on the other hand, rented his calves and placed them 
again on the market a short time after the vaccine material was taken. 
In this way the disease spread from the vaccine stables of Manufac- 
turer A, but not from those of Manufacturer B, although it was the 
vaccine virus from the latter establishment that infected the former's 
cattle. 

DIFFERENTIAL DIAGNOSIS. 

The clinical picture presented by the first few animals of the first 
series of experiments and tvv'o of the animals in the third series of 
experiments was somewhat confusing at first, as the disease appeared 
in such a benign form and the lesions were far from being typical, 
and further appeared at rather irregular intervals over a number of 
successive days rather than within a relatively short and definite 
period of time. We have no exphmation to make of this except the 
fact that we were at first working with a decidedly attenuated virus 
of the disease. While a mistake might be made in these early cases 
because of the slow infection of the animal, the failure to transmit 
the disease by cohabitation, tlie presence of suggestive though atypical 
lesions, the absence of the characteristic vesicles and foot lesions in 
some of the cases, and the very conspicuous absence of general symp- 
toms, especially drooling, inappetence, high temperature, and great 
loss of flesh, still such lesions as were observed must, in the light of 
our present knowledge, be considered as highly suggestive of foot- 
and-mouth disease. 

The lesions, however, which occurred in calves 609 and 611 of the 
third series of experiments, sheep 1, 2, and 3 of the seco'nd series, and 
cows 375 and 630 and calves 677 and 614 of the first series were so 
entirely typical and the symptoms manifested in some of these ani- 
mals were so true to the natural disease that in these cases there was 
no question of the diagnosis, and it so happtoed that three or more 
of these cases were observed and the diagnosis confirmed by Drs. 
Melvin, McEachran, Law, Pearson, White, Schroeder, Bennett, Hick- 
man, Washburn, Eichhorn, Ditewig, Formad, and several others who 
have had experience with foot-and-mouth disease. 

Vaccinia or cowpox was eliminated in the diagnosis by using in 
each series of experiments animals that had recovered from, and were 
therefore immune to, that disease. Furthermore, scrapings from the 
lesions were used for inoculating the scrotum of guinea pigs and the 
cornea of rabbits, but without producing any lesions of vaccinia. 

Necrotic stomatitis may likewise be eliminated, as subcutaneous in- 
oculations of rabbits were made in a number of instances for the 



OEIGIN OF 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 21 

isolation of the Bacillus necrophorus, but with negative results in 
each case. 

^' Mycotic stomatitis was also discarded as a possible diagnosis, as the 
disease contaminating the vaccine virus even in the early cases was 
proven to be infectious and transmissible by inoculation, which is 
not possible with mycotic stomatitis. Furthermore, the sheep inocu- 
lated with this virus failed to develop any indications whatsoever of 
a stomatitis, but instead showed well-marked and typical lesions of 
the feet. This latter condition is one of the peculiar though charac- 
teristic features of foot-and-mouth disease, for while the disease 
attacks the mouths and less frequently the feet of cattle, it seems to 
be localized almost exclusively in the feet of sheep. 

Eelation of Foot-and-Mouth Disease to Vaccine Virus. 

Loeffler and Froesch^ in their researches upon foot-and-mouth 
disease show that the surest mode of infection is by the introduction 
of the contents of a vesicle into the circulation. It is also possible 
to infect by injecting the virus into the peritoneal cavity or into the 
musculature or by rubbing it into a scarification of the mucous 
membrane. On the other hand, if the virus is introduced into or 
under the skin, infection is very uncertain even in cattle, which are 
most susceptible to the disease. Infection in the latter instance seems 
to occur only if there is injury to the smaller blood vessels. 

Loeffler and Froesch inoculated animals (cattle) with a mixture of 
vaccine virus and lymph from a foot-and-mouth vesicle. The result 
was that the animals vaccinated with this mixture only showed local 
reaction of vaccinia and did not develop foot-and-mouth disease. 
The authors further show that cowpox does not protect against 
foot-and-mouth disease, nor does foot-and-mouth disease protect 
against cowpox. They further observed that when animals are inocu- 
ulated with a mixture of the two viruses they only sicken with the 
general infection of foot-and-mouth disease provided blood is drawn 
in the cutaneous scarifications. 

Hecker,- in charge of the Saxony commission established for the 
study of this disease, failed to produce foot-and-mouth disease by 
rubbing the virus upon the healthy skin or by tying infected cotton 
pads to the clefts of the feet. 

Recently Starcovici^ has conducted a number of experiments with 
the purpose of attenuating outbreaks of foot-and-mouth disease by 
the inoculation of the cattle with cowpox virus. This work was 
based upon the report of Ory, who communicated to the Societe 
Central de Medecine Veterinaire in Paris that material from a natu- 

1 Centralblatt fiir BakterIolog:ie, etc., 1. abt., vol. 23, 1898, pp. 371-391. 
*Zeitschrift dor Landwirtschaftskammer fiir die Provinz Sachsen, No. 3, 1899. 
« Archlva Veterinaria, Nos. 4 and 5, Vol. V, p. 203. 



22 ORIGIN OF 1908 OUTBREAK OF FOOT-AND-MOUTH DISEASE. 

ral case of horsepox inoculated by cutaneous scarification into cattle 
confers upon them an immunity against foot-and-mouth disease. In 
repeating these experiments, however, Starcovici noted that the 
influence of either horsepox or cowpox upon the development of 
foot-and-mouth disease was but slight, for while the injected ani- 
mals resisted exposure for an unusually long period (18 to 20 days), 
this alone would not make such vaccination practicable. With this 
end in view he prepared a mixture of 2 parts of cowpox virus, 2 parts 
of normal serum, and 1 partr of foot-and-mouth disease lymph. By 
the injection of this mixture he succeeded in transmitting a very 
mild form of foot-and-mouth disease in 83 per cent of the cases, 
and even during the course of the disease the cattle were worked in 
the yoke. 

In another series of experiments a mild or benign form of the 
disease was conveyed in 82 per cent of the cases. It was also ob- 
served that foot lesions developed only in 2 out of 17 cases, and these 
lesions were slight, while in the natural foot-and-mouth disease the 
foot lesions attain a proportion of from GO to TO or even 80 per cent. 

As a result of these experiments Starcovici believes that with his 
mixture, which contains cowpox virus, a benign form of foot-and- 
mouth disease may be given, as a result of which the animals may be 
utilized without interruption in agricultural work. 

Our experiments likewise indicate quite plainly that the foot-and- 
mouth infection in the glycerinated vaccine virus is dilute and 
attenuated. We have shown that the vaccine virus of Manufacturer 
B contained the infection of foot-and-mouth disease, and that this 
has existed at least since April 15, 1908, and probably a much longer 
time. However, no instance of the transmission of foot-and-mouth 
disease to man through vaccine virus has been recorded, and it is 
doubtful, in view of the evidence submitted, if it is possible to repro- 
duce the disease in him by the cutaneous inoculation commonly used 
in the process of vaccination. Moreover, man is not very susceptible 
to the disease, and it would therefore seem that the virus thus con- 
taminated may be characterized as undesirable rather than dangerous 
to man. 

However, as soon as the facts became known immediate and 
effectual steps were taken by Surg. Gen. AValter Wyman, of the 
United States Public Health and ISIarine-Hospital Service, to eradi- 
cate all this vaccine virus used in America. Under the law of July 
1, 1902, the licenses of Manufacturers A and B were at once sus- 
pended, and all the suspected vaccine virus on hand was destroyed 
and that upon the market withdrawn, and other measures of a radical 
nature were taken to accomplish the desired object. In this process 
the intelligent and prompt cooperation of these firms is much to be 
commended. Further, the Hj'-gienic Laboratory was directed by tho 



OKIGIN OF 1908 OUTBREAK OP FOOT-AND-MOUTH DISEASE. 23 

Surgeon General to examine at once every strain of vaccine virus 
upon the market to determine whether it was free from this infec- 
tion. This has been done, and it may be stated that there is now 
upon the market no vaccine virus contamiiiated with the virus of 
foot-and-mouth disease. In fact, the contamination of Manufac- 
turer A's vaccine was established while it was still undergoing the 
ripening process and before it had been placed on the market. 

Hereafter manufacturers will be required to test their virus for 
the presence of foot-and-mouth infection, as they are now required 
to test it for the presence of tetanus and other pathogenic micro- 
organisms. Similar control tests will be made in the Hygienic Labo- 
ratory under the law to insure the purity and potency of the vaccine 
virus that is found in interstate traffic. 

Furthermore, additional regulations have been issued, in accord- 
ance with section 4 of the act approved July 1, 1902, having for their 
specific object the prevention of the importation, or the sale in inter- 
state traffic, of vaccine virus contaminated with foot-and-mouth dis- 
ease or other infections communicable to man. 

Conclusions. 

(1) The recent outbreak of foot-and-mouth disease in this country 
started from some calves used to propagate vaccine virus. 

(2) The vaccine virus used on these calves has been proved to 
contain the infection of foot-and-mouth disease. 

(3) The outbrealcs of foot-and-mouth disease in 1902-3 probably 
had a similar origin. 

(4) It is probable that the foot-and-mouth infection got into the 
vaccine virus in some foreign country where the disease prevailed, 
and was introduced into the United States through the importation 
of this contaminated vaccine..... 

(5) The symbiosis between the infections of vaccinia and foot- 
and-mouth disease is especially interesting. Animals vaccinated with 
the mixed virus, as a rule, show only the lesions of one of these dis- 
eases, namely, vaccinia ; nevertheless the infectious principle of foot- 
and-mouth disease remains in the vaccinal eruption. 



WASHINGTON : GOVERNMBNT PESINTING OFFICE : 1913 



LIBRARY OF CONGRESS 



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